A supported catalyst obtained by supporting a catalyst metal on a carrier is used in many fields and is used as a catalyst for exhaust gas purification, liquid-phase chemical synthesis reaction, gas-phase chemical synthesis reaction, fuel cell reaction, etc.
As to such a supported catalyst, it is known that the size of the catalyst metal particles supported on a carrier is important. In this connection, for example, Patent Document 1 has proposed a supported catalyst in which catalyst metal particles having a size of 1 to 10 nm are supported on a carrier of alumina, silica, titania, zirconia or a combination thereof. In addition, Patent Document 2 has proposed a catalyst for nitrogen oxide, in which copper ion is supported on zeolite by ion exchange. Furthermore, Patent Document 3 has proposed a technique where palladium supported on zeolite by ion exchange is dried and then clustered by a reduction treatment to prepare a cluster-supporting catalyst, and the cluster-supporting catalyst is used for a coupling reaction, etc.
Incidentally, Patent Document 4 finds that zeolite structure collapses by migration of aluminum atom from the zeolite structure in a high temperature atmosphere containing water vapor such as an exhaust gas atmosphere, and proposes improving heat resistance of zeolite as a catalyst carrier by substituting at least part of aluminum atom in aluminosilicate zeolite with boron atom, calcium atom, indium atom, etc.
Further, in Patent Document 5, which is not disclosed at the filing date of the priority application of the present application, discloses a cluster-supporting catalyst comprising porous carrier particles having acid sites such as zeolite, and catalyst metal clusters supported within the pores of the porous carrier particles; and a method for producing the same.
Incidentally, it is known that boron-substituted zeolite, i.e. zeolite having a structure in which at least part of aluminum atom constituting aluminosilicate zeolite is substituted with boron atom, can be obtain by the method disclosed in Non-Patent Document 1.